Rep. Peter Welch, Vermont Democrat, says Congress is short-circuiting the standard review process in taking up legislation authorizing the construction of the Keystone XL oil pipeline and that the project has gotten bogged down in the politics of the U.S. Senate race in Louisiana.

“When you do have a major pipeline, there is a process that is followed, and essentially what Congress has done is acted like a playing board with 535 of us here — we’re acting as though we can exempt this project from the standard review process,” Mr. Welch said on CNN’s “New Day.”

Mr. Welch also said Congress is effectively giving an “earmark” to TransCanada Corp., which would get the right to build the pipeline, by saying the company doesn’t have to pay into a mitigation fund in the event there is an environmental spill.

Backers of the pipeline, though, have said President Obama has politicized the review process, needlessly drawing it out even though the State Department has concluded it would be safe and wouldn’t contribute significantly to greenhouse gases.

“And then third, this is really about politics,” Mr. Welch said. “We’ve got a Republican in the House who’s running for the U.S. Senate in Louisiana. We’ve got a Democrat in the Senate in Louisiana running desperately for re-election, and this is all about getting one or the other of them an [edge], and that’s not the way we should be making a decision on a major pipeline that is going through environmentally sensitive areas.”

Indeed, the House-cleared legislation that granted TransCanada the right to build the pipeline last week was sponsored by GOP Rep. Bill Cassidy. Mr. Cassidy is facing Democratic Sen. Mary Landrieu, who is working furiously to gather the 60 votes needed to advance legislation in the Senate, in a Dec. 6 runoff.